docs: def clock_in(request):
      """For clocking the user into a project."""
      user = request.user
      # Lock the active entry for the duration of this transaction, to prevent
      # creating multiple active entries.
      active_entry = utils.get_active_entry(user, select_for_update=True)
  
      initial = dict([(k, v) for k, v in request.GET.items()])
      data = request.POST or None
      form = ClockInForm(data, initial=initial, user=user, active=active_entry)
      if form.is_valid():
          entry = form.save()
          message = 'You have clocked into {0} on {1}.'.format(
              entry.activity.name, entry.project)
          messages.info(request, message)
          return HttpResponseRedirect(reverse('dashboard'))
  
      return render(request, 'timepiece/entry/clock_in.html', {
          'form': form,
          'active': active_entry,
      })